1. Field of the Invention
The present invention relates to a mechanism for blocking a roll-up device for safety belts in motor vehicles responsive to a danger sensor reacting to a dangerous situation. The roll-up device has a ratchet wheel firmly connected to the belt shaft and a blocking pawl which can be swung into the tooth area of the former, as well as a control pawl which, in conjunction with a control disc is arranged as a control between the danger sensor and the blocking pawl. The control disc and the ratchet wheel are rigidly connected to each other and have the same number of teeth.
2. Description of the Prior Art
In motor vehicles, safety belts are used to protect the passengers from injuries due to an accident. The safety belts are connected, on one side, to a mechanism for rolling-up the safety belt and holding it taut. Into this mechanism is built a device which is capable of blocking this mechanism and thereby also the safety belt in the event of an extreme acceleration or deceleration force normally occurring in accidents which acts on the motor vehicle or the motor vehicle passenger and actuates a built-in danger sensor. The danger sensor senses additional dangerous situations independent of sudden speeding and stopping, such as tilting of the motor vehicles which may result in overturning the vehicle, or in crashes in which the vehicle is traveling at a legal speed or even standing still.
In the simplest embodiment, the blocking process can be effected by having the danger sensor act directly on a pawl which drops into the region of the teeth of a ratchet wheel firmly arranged on the belt shaft. This simple design and operation has the disadvantage that the dropping-in motion of the pawl into the teeth of the ratchet wheel can take place independently of the respective rotational position of the ratchet wheel relative to the pawl. Therefore, the danger exists that the pawl falls only or very frequently on the top region of a tooth of the ratchet wheel, and the large forces to be intercepted are conducted via this narrow top region. This leads to heavy wear, if not to destruction of the pawl and the teeth of the ratchet wheel.
Therefore, devices have contrived for the purpose of counteracting this shortcoming. Normally, an intermediate mechanism is built-in between the danger sensor and the blocking pawl for blocking the ratchet wheel and thereby the belt shaft. The intermediate mechanism controls the blocking pawl such that it drops into the teeth of the ratchet wheel at the instant which ensures that the entire active area of the blocking pawl and the respective tooth of the ratchet wheel will be fully engaged when the force is transmitted. For this purpose, a control pawl is normally used which acts on a control disc which, in turn, controls the dropping-in motion of the blocking pawl.
German Published Non-Prosecuted application DE-OS 30 06 177 discloses a locking device for safety belt roll-up devices, especially for motor vehicles, in which the cam (control disc) and ratchet wheel rigidly connected to each other have the same number of teeth. The control lever is arranged with its area of engagement into the cam and with its stationary fulcrum radially to the cam. A pawl can be swung into the teeth of the ratchet wheel via a driver extension at this control lever, if the control lever is swung by a danger sensor into the teeth of the control disc and is continued in its swing by the rotation carried out via the control disc. This embodiment requires considerable space.